1. Field of the Invention
The present invention generally relates to optical device and optical apparatus, in particular, to a lens and a light source apparatus.
2. Description of Related Art
As the development in optical technology, more and more the light shapes of light source apparatus for providing illumination has been developed. For the light emitting device in the light source apparatus, such as light emitting die or filament, the variations of the illuminating light shape as provided are relatively few. To provide more probabilities for the light shape, the technology for the lens with various proper shapes and configured on the light path of the light emitting device to provide the proper light shape has been the concerning issue for development in the field of illumination.
In recent years, the light emitting efficiency and the lifetime of the light emitting diode (LED) has been improved. In addition, it has the device properties of low power consumption, low contamination, high efficiency, high response rate, small volume, light, capability of configuring on various surfaces, and so on. The LED has been applied to various optical fields with great intention. Generally, the LED can be applied to various illumination devices in the daily life and various flat displaying apparatus, such as the light source for the liquid crystal display (LCD). Since the LED has the properties of small volume, long life time, low power consumption as stated above, the system performance of the backlight module can be effectively improved if the LED is applied in the backlight module.
However, the LED is a light source having a direction for emitting light, so the region with direct illumination in front of the LED light source usually has relatively high luminance and the luminance at the region without direct illumination is less than the luminance at the region with direct illumination. When the LED light source is applied to the backlight module, the luminance uniformity within the effective illumination region would be affected, and the image quality of the display would be then affected.